Acute inorganic mercury vapor inhalation poisoning

Mercury contamination is a serious environmental problem worldwide. Two pri mary sources of contamination are dumping of large quantities of inorganic mercury and exposure in the mining industry. Although the actual fatal leve l of mercury vapor is not known, exposure to more than 1-2 mg/m(3) of eleme ntal mercury vapor (Hg-0) for a few hours causes acute chemical bronchiolit is and pneumonitis. Two hours after exposure, lung injury appears as hyalin e membrane formation, and finally, extensive pulmonary fibrosis occurs. Cli nical findings correlate with the duration of exposure, the concentration o f mercury, and the survival time after exposure. There is no correlation be tween pathological findings and the concentration of mercury in the tissues . Necrosis of proximal convoluted tubules may be attributed to the disrupti on of the enzyme systems of Hg2+-sulfhydryl compounds. Metallothionein prot ein (MT), induced by the accumulation of Hg2+ in the kidneys, may play an i mportant role in detoxication after it forms a non-toxic Hg2+-MT compound. Despite the deposition of mercury in the brain, compared with organic mercu ry, inorganic mercury did not seem to damage the neurons. Drugs such as che lating agents and corticosteroids appear to effectively decrease the inflam mation and delay pulmonary fibrosis.